SYMBOLCOMMON_NAMEaka. SYNONYMS
win.yarat (Back to overview)

YaRAT

Actor(s): APT31


According to PTSecurity, this RAT uses Yandex Disk as a C2.

References
2022-08-04PTSecurityPT ESC Threat Intelligence
@online{intelligence:20220804:flying:99dfe7f, author = {PT ESC Threat Intelligence}, title = {{Flying in the clouds: APT31 renews its attacks on Russian companies through cloud storage}}, date = {2022-08-04}, organization = {PTSecurity}, url = {https://www.ptsecurity.com/ww-en/analytics/pt-esc-threat-intelligence/apt31-cloud-attacks}, language = {English}, urldate = {2022-08-09} } Flying in the clouds: APT31 renews its attacks on Russian companies through cloud storage
Stealer0x3401 YaRAT
2022-08-04PTSecurityPT Expert Security Center
@online{center:20220804:flying:a16b831, author = {PT Expert Security Center}, title = {{Flying in the clouds: APT31 renews its attacks on Russian companies through cloud storage}}, date = {2022-08-04}, organization = {PTSecurity}, url = {https://www.ptsecurity.com/ww-en/analytics/pt-esc-threat-intelligence/apt31-cloud-attacks/}, language = {English}, urldate = {2022-08-15} } Flying in the clouds: APT31 renews its attacks on Russian companies through cloud storage
Stealer0x3401 YaRAT
Yara Rules
[TLP:WHITE] win_yarat_auto (20230125 | Detects win.yarat.)
rule win_yarat_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-01-25"
        version = "1"
        description = "Detects win.yarat."
        info = "autogenerated rule brought to you by yara-signator"
        tool = "yara-signator v0.6.0"
        signator_config = "callsandjumps;datarefs;binvalue"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.yarat"
        malpedia_rule_date = "20230124"
        malpedia_hash = "2ee0eebba83dce3d019a90519f2f972c0fcf9686"
        malpedia_version = "20230125"
        malpedia_license = "CC BY-SA 4.0"
        malpedia_sharing = "TLP:WHITE"

    /* DISCLAIMER
     * The strings used in this rule have been automatically selected from the
     * disassembly of memory dumps and unpacked files, using YARA-Signator.
     * The code and documentation is published here:
     * https://github.com/fxb-cocacoding/yara-signator
     * As Malpedia is used as data source, please note that for a given
     * number of families, only single samples are documented.
     * This likely impacts the degree of generalization these rules will offer.
     * Take the described generation method also into consideration when you
     * apply the rules in your use cases and assign them confidence levels.
     */


    strings:
        $sequence_0 = { 85ff 0f8486feffff 8bb370040000 8d8594feffff 8b5604 8d4a08 51 }
            // n = 7, score = 100
            //   85ff                 | test                edi, edi
            //   0f8486feffff         | je                  0xfffffe8c
            //   8bb370040000         | mov                 esi, dword ptr [ebx + 0x470]
            //   8d8594feffff         | lea                 eax, [ebp - 0x16c]
            //   8b5604               | mov                 edx, dword ptr [esi + 4]
            //   8d4a08               | lea                 ecx, [edx + 8]
            //   51                   | push                ecx

        $sequence_1 = { c0c06c 661da314 2bc4 89542500 660fbaf013 f8 8b06 }
            // n = 7, score = 100
            //   c0c06c               | rol                 al, 0x6c
            //   661da314             | sbb                 ax, 0x14a3
            //   2bc4                 | sub                 eax, esp
            //   89542500             | mov                 dword ptr [ebp], edx
            //   660fbaf013           | btr                 ax, 0x13
            //   f8                   | clc                 
            //   8b06                 | mov                 eax, dword ptr [esi]

        $sequence_2 = { ff75e0 8d4de8 e8???????? 8b7dc8 ff75d4 e8???????? 57 }
            // n = 7, score = 100
            //   ff75e0               | push                dword ptr [ebp - 0x20]
            //   8d4de8               | lea                 ecx, [ebp - 0x18]
            //   e8????????           |                     
            //   8b7dc8               | mov                 edi, dword ptr [ebp - 0x38]
            //   ff75d4               | push                dword ptr [ebp - 0x2c]
            //   e8????????           |                     
            //   57                   | push                edi

        $sequence_3 = { d1c8 48 f8 35286e4d10 f5 f6c6d7 33d8 }
            // n = 7, score = 100
            //   d1c8                 | ror                 eax, 1
            //   48                   | dec                 eax
            //   f8                   | clc                 
            //   35286e4d10           | xor                 eax, 0x104d6e28
            //   f5                   | cmc                 
            //   f6c6d7               | test                dh, 0xd7
            //   33d8                 | xor                 ebx, eax

        $sequence_4 = { e8???????? 4a 6685fe f5 0fca f9 85cf }
            // n = 7, score = 100
            //   e8????????           |                     
            //   4a                   | dec                 edx
            //   6685fe               | test                si, di
            //   f5                   | cmc                 
            //   0fca                 | bswap               edx
            //   f9                   | stc                 
            //   85cf                 | test                edi, ecx

        $sequence_5 = { e8???????? 56 e8???????? 83c40c 8bd8 5f 5e }
            // n = 7, score = 100
            //   e8????????           |                     
            //   56                   | push                esi
            //   e8????????           |                     
            //   83c40c               | add                 esp, 0xc
            //   8bd8                 | mov                 ebx, eax
            //   5f                   | pop                 edi
            //   5e                   | pop                 esi

        $sequence_6 = { 8bd0 83c418 85d2 756c ff75fc 6a07 ff7510 }
            // n = 7, score = 100
            //   8bd0                 | mov                 edx, eax
            //   83c418               | add                 esp, 0x18
            //   85d2                 | test                edx, edx
            //   756c                 | jne                 0x6e
            //   ff75fc               | push                dword ptr [ebp - 4]
            //   6a07                 | push                7
            //   ff7510               | push                dword ptr [ebp + 0x10]

        $sequence_7 = { c68528feffff00 83fa10 722f 8b8d04feffff 42 8bc1 81fa00100000 }
            // n = 7, score = 100
            //   c68528feffff00       | mov                 byte ptr [ebp - 0x1d8], 0
            //   83fa10               | cmp                 edx, 0x10
            //   722f                 | jb                  0x31
            //   8b8d04feffff         | mov                 ecx, dword ptr [ebp - 0x1fc]
            //   42                   | inc                 edx
            //   8bc1                 | mov                 eax, ecx
            //   81fa00100000         | cmp                 edx, 0x1000

        $sequence_8 = { 895f08 894f04 0fa4f028 8917 80e33b c1f811 5b }
            // n = 7, score = 100
            //   895f08               | mov                 dword ptr [edi + 8], ebx
            //   894f04               | mov                 dword ptr [edi + 4], ecx
            //   0fa4f028             | shld                eax, esi, 0x28
            //   8917                 | mov                 dword ptr [edi], edx
            //   80e33b               | and                 bl, 0x3b
            //   c1f811               | sar                 eax, 0x11
            //   5b                   | pop                 ebx

        $sequence_9 = { 56 57 8b38 8b450c 8b4f0c 8b18 85c9 }
            // n = 7, score = 100
            //   56                   | push                esi
            //   57                   | push                edi
            //   8b38                 | mov                 edi, dword ptr [eax]
            //   8b450c               | mov                 eax, dword ptr [ebp + 0xc]
            //   8b4f0c               | mov                 ecx, dword ptr [edi + 0xc]
            //   8b18                 | mov                 ebx, dword ptr [eax]
            //   85c9                 | test                ecx, ecx

    condition:
        7 of them and filesize < 8692736
}
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